When one-click printing (direct printing) is enabled, the Printing service status in the direct printing settings should show as 'Connected' with a ticked checkbox, and you should see a ticked checkbox icon in print buttons in Provet. If there is no connection, try the following:
In Settings > General > Integrations > Direct printing, select the Refresh button.
Check that the One-click printer type in Provet settings and the Type in Provet ProPrint (for Windows) or Provet ProPrint (for macOS) configuration match exactly.
The system will output status and error messages to your web browser's JavaScript console. Check these for any hints.